The present invention is directed to an apparatus and method which is used to evaluate the effect of solder substances on a printed circuit board populated with electronic components. Specifically, a test circuit board assembly is disclosed which when subject to a solder process, is useful for measuring the effects of the soldering process on circuit testability.
The processes for manufacturing printed circuit boards having mounted components interconnected by circuit conductors influences the circuit board test ability following manufacture. When changes to printed circuit board manufacturing assembly processes occur, such as changing fluxes and solder pastes which may require water cleaning of the circuit board, to fluxes and solder pastes which are designed not to be cleaned from the circuit board, the ability to test the circuit board assembly by conventional product testing facilities changes. While the changes to the processes may in fact not effect the circuit operation, the ability to test the circuit board assembly may be impaired.
Testing of completed circuit board assemblies conventionally requires a set of probes which are applied to the circuit conductors on the circuit board. The probes are of different design, and some may for a given solder processes, provide a better connection to a circuit board concuctor than others. Processes which involve the use of so-called no-clean fluxes and solder pastes, which are not to be removed from the printed circuit board, may pose a problem for testing the final product. While the residue from the no-clean flux and solder paste is not detrimental to product performance, the probes from a tester may not adequately make contact with the circuit board conductor when covered by a residue.
Because of the wide availability of different types of clean and no-clean fluxes and solder pastes, it is desirable to provide a common test vehicle which can evaluate the impact on testability for the use of any of these fluxes and solder pastes, and processes for soldering circuit board assemblies with these fluxes and solder pastes.
The testability of a circuit board assembly depends on the particular types of components being soldered to the surface of a board. Thus, while one component type may show no effects on testability after the use of a new no-clean flux and solder paste, other components may in fact make testability very difficult and unreliable.
The present invention provides a way for evaluating these processes prior to committing to any significant production of circuit boards.